I was thinking more along the lines of this;
UNITED STATES CODE, TITLE 36, CHAPTER 10
§171.
Conduct during playing
During rendition of the national anthem when the flag is displayed, all present except those in uniform should stand at attention facing the flag with the right hand over the heart. Men not in uniform should remove their headdress with their right hand and hold it at the left shoulder, the hand being over the heart. Persons in uniform should render the military salute at the first note of the anthem and retain this position until the last note. When the flag is not displayed, those present should face toward the music and act in the same manner they would if the flag were displayed there.
USFlag.org: A website dedicated to the Flag of the United States of America - United States Code